JP2009098402A - Fixing apparatus, image forming apparatus, and frame - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing apparatus causing no abnormal noise due to contact between a frame and a bearing, and to provide an image forming apparatus and the frame. <P>SOLUTION: The fixing apparatus includes bearings 43, 44 installed at both end shaft parts 21a, 31a of two roller members, and frames 41, 42 having hole parts 41a, 42a holding the bearings 43, 44 and supporting the two roller members rotatably through the bearings 43, 44. The hole parts 41a, 42a of the frames 41, 42 are provided with non-abutting parts 41a2, 42a2 formed so that the bearings 43, 44 do not abut on the hole parts 41a, 42a on the facing side of the two roller members, and abutting parts 41a1, 42a1 formed so that the bearings 43, 44 abut on the hole parts 41a, 42a on the opposite side to the facing side of the two roller members. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, or a complex machine thereof, a fixing device installed therein, and a frame of the fixing device.

  2. Description of the Related Art Conventionally, in a fixing device installed in an image forming apparatus such as a copying machine or a printer, a technique for forming a nip portion in which a recording medium is conveyed by press-contacting two roller members (for example, patents) is known. Reference 1 to 3).

  Such a fixing device includes two roller members (a fixing roller and a pressure roller), a pressure unit that presses the two roller members, a heater that heats the fixing roller (heating roller), an excitation coil, and the like. A heating means, a frame that rotatably supports two roller members via a bearing such as a ball bearing, and the like are configured. Then, the fixing roller is heated by the heating unit, and the toner image on the recording medium conveyed toward the nip portion receives heat and pressure and is fixed on the recording medium.

JP 2006-337901 A JP 2006-343463 A JP 2005-292644 A

  The conventional fixing device described above is configured such that the bearing is in contact with almost the entire circumferential direction with respect to the hole portion of the frame, and abnormal noise may occur due to contact between the frame and the bearing.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to provide a fixing device, an image forming apparatus, and a frame that do not cause abnormal noise due to contact between the frame and a bearing. .

  The fixing device according to the first aspect of the present invention is a fixing device that heats and melts a toner image and fixes the toner image on a recording medium. Two roller members, bearings respectively installed at both end shafts of the two roller members, and holes for holding the bearings, and rotating the two roller members via the bearings A frame that freely supports, and the hole portion of the frame has a non-contact portion formed so that the bearing does not contact the hole portion on a side where the two roller members face each other, An abutting portion formed so that the bearing abuts against the hole portion on the opposite side to the side where the two roller members face each other.

  The fixing device according to a second aspect of the present invention is the fixing device according to the first aspect, wherein the non-contact portion of the hole portion corresponds to an imaginary line segment connecting the rotation centers of the two roller members. And formed over a range of ± 90 degrees or more.

  According to a third aspect of the present invention, in the fixing device according to the second aspect, the non-contact portion of the hole is formed over a range of ± 140 degrees or less with respect to the virtual line segment. It has been done.

  The fixing device according to a fourth aspect of the present invention is the fixing device according to any one of the first to third aspects, wherein the contact portion of the hole is divided into a plurality in the circumferential direction. It is.

  According to a fifth aspect of the present invention, there is provided the fixing device according to any one of the first to fourth aspects, wherein the contact portion of the hole is coated with grease.

  A fixing device according to a sixth aspect of the present invention is the fixing device according to the fifth aspect, wherein the grease is fluorine grease.

  The fixing device according to a seventh aspect of the present invention is the fixing device according to any one of the first to sixth aspects, wherein the bearing interferes with the frame and moves in the rotation axis direction with respect to the roller member. It is provided with a brim portion that regulates.

  The fixing device according to an eighth aspect of the present invention is the fixing device according to any one of the first to seventh aspects, wherein the shaft portion of the roller member is in a rotational axis direction of the bearing with respect to the roller member. Retaining rings that restrict the movement of the door are installed.

  The fixing device according to a ninth aspect of the present invention is the fixing device according to any one of the first to eighth aspects, wherein the shaft portion of the roller member is in a rotational axis direction of the bearing with respect to the roller member. The step part which regulates the movement of is formed.

  A fixing device according to a tenth aspect of the present invention is the fixing device according to any one of the first to ninth aspects, wherein the bearing is press-fitted into the shaft portion of the roller member.

  According to an eleventh aspect of the present invention, in the fixing device according to the tenth aspect, the shaft portion of the roller member is formed so that the hardness thereof is 70 HV or more.

  The fixing device according to a twelfth aspect of the present invention is the fixing device according to any one of the first to eleventh aspects, wherein the non-contact portion of the hole portion has an inner diameter that is the outer diameter of the bearing. The contact portion of the hole is formed so that the inner diameter thereof is the same as the outer diameter of the bearing.

  A fixing device according to a thirteenth aspect of the present invention is the fixing device according to any one of the first to twelfth aspects, wherein the frame is divided for each of the two roller members.

  According to a fifteenth aspect of the present invention, in the fixing device according to any one of the first to thirteenth aspects, the frame is installed independently at both ends of the two roller members. Is.

  According to a fifteenth aspect of the present invention, there is provided a fixing device according to any one of the first to fourteenth aspects, wherein the two roller members are a fixing roller and a pressure roller. is there.

  The fixing device according to a sixteenth aspect of the present invention is the fixing device according to any one of the first to fourteenth aspects, wherein the two roller members are pressed against each other via an endless belt member. A nip portion is formed.

  According to a seventeenth aspect of the present invention, an image forming apparatus includes the fixing device according to any one of the first to sixteenth aspects.

  A frame according to an eighteenth aspect of the present invention is a frame installed in a fixing device that heats and melts a toner image and fixes the toner image on the recording medium. Each of the two roller members that form a nip portion to which the two roller members are conveyed, each of which is provided with a hole portion that holds a bearing. The two roller members are rotatably supported via the bearing, and the holes The non-contact portion formed so that the bearing does not contact the hole on the side where the two roller members face each other, and the bearing on the opposite side to the side where the two roller members face each other. And an abutting portion formed to abut against the hole portion.

  In the present invention, since the non-contact portion is provided in the hole portion of the frame so that the bearing does not contact the hole portion on the side where the two roller members face each other, the contact area between the frame and the bearing is reduced. This makes it easier for the bearing to move in the thrust direction and makes it difficult to interfere with the frame even if the bearing vibrates in the eccentric direction. Accordingly, it is possible to provide a fixing device, an image forming apparatus, and a frame in which abnormal noise due to contact between the frame and the bearing does not occur.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

Embodiment 1 FIG.
A first embodiment of the present invention will be described in detail with reference to FIGS.
First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG.
As shown in FIG. 1, the image forming apparatus 1 according to the first embodiment is a tandem type color printer. Four bottles 102Y, 102M, 102C, and 102K corresponding to the respective colors (yellow, magenta, cyan, and black) are detachably (replaceable) installed in the bottle housing portion 101 above the image forming apparatus main body 1. ing.
An intermediate transfer unit 85 is disposed below the bottle housing portion 101. Image forming units 4Y, 4M, 4C, and 4K corresponding to the respective colors (yellow, magenta, cyan, and black) are arranged in parallel so as to face the intermediate transfer belt 78 of the intermediate transfer unit 85.

  Photosensitive drums 5Y, 5M, 5C, and 5K are disposed in the image forming units 4Y, 4M, 4C, and 4K, respectively. Further, around each of the photosensitive drums 5Y, 5M, 5C, and 5K, a charging unit 75, a developing unit 76, a cleaning unit 77, a charge eliminating unit (not shown), and the like are disposed. Then, an image forming process (charging process, exposure process, development process, transfer process, cleaning process) is performed on each of the photoconductive drums 5Y, 5M, 5C, and 5K. An image of each color is formed on 5K.

The photosensitive drums 5Y, 5M, 5C, and 5K are rotationally driven in a clockwise direction in FIG. 1 by a drive motor (not shown). Then, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K are uniformly charged at the position of the charging unit 75 (a charging process).
Thereafter, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach the irradiation position of the laser light L emitted from the exposure unit 3, and electrostatic latent images corresponding to the respective colors are formed by exposure scanning at this position. (It is an exposure process.)

Thereafter, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach a position facing the developing device 76, and the electrostatic latent image is developed at this position to form toner images of each color (development process). .)
Thereafter, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach the positions facing the intermediate transfer belt 78 and the first transfer bias rollers 79Y, 79M, 79C, and 79K, and at these positions, the photosensitive drums 5Y, 5M, and so on. The toner images on 5C and 5K are transferred onto the intermediate transfer belt 78 (this is a primary transfer process). At this time, a small amount of untransferred toner remains on the photosensitive drums 5Y, 5M, 5C, and 5K.

Thereafter, the surfaces of the photoconductive drums 5Y, 5M, 5C, and 5K reach a position facing the cleaning unit 77, and untransferred toner remaining on the photoconductive drums 5Y, 5M, 5C, and 5K is removed at this position. 77 is mechanically collected by a cleaning blade (cleaning process).
Finally, the surfaces of the photoconductive drums 5Y, 5M, 5C, and 5K reach a position facing a neutralization unit (not shown), and the residual potential on the photoconductive drums 5Y, 5M, 5C, and 5K is removed at this position. The
Thus, a series of image forming processes performed on the photosensitive drums 5Y, 5M, 5C, and 5K is completed.

Thereafter, the toner images of the respective colors formed on the respective photosensitive drums through the developing process are transferred onto the intermediate transfer belt 78 in an overlapping manner. In this way, a color image is formed on the intermediate transfer belt 78.
Here, the intermediate transfer unit 85 includes an intermediate transfer belt 78, four primary transfer bias rollers 79Y, 79M, 79C, and 79K, a secondary transfer backup roller 82, a cleaning backup roller 83, a tension roller 84, and an intermediate transfer cleaning unit 80. , Etc. The intermediate transfer belt 78 is stretched and supported by the three rollers 82 to 84 and is endlessly moved in the direction of the arrow in FIG.

The four primary transfer bias rollers 79Y, 79M, 79C, and 79K sandwich the intermediate transfer belt 78 with the photosensitive drums 5Y, 5M, 5C, and 5K, respectively, thereby forming primary transfer nips. Then, a transfer bias reverse to the polarity of the toner is applied to the primary transfer bias rollers 79Y, 79M, 79C, and 79K.
The intermediate transfer belt 78 travels in the direction of the arrow and sequentially passes through the primary transfer nips of the primary transfer bias rollers 79Y, 79M, 79C, and 79K. In this way, the toner images of the respective colors on the photosensitive drums 5Y, 5M, 5C, and 5K are primarily transferred while being superimposed on the intermediate transfer belt 78.

Thereafter, the intermediate transfer belt 78 onto which the toner images of the respective colors are transferred in an overlapping manner reaches a position facing the secondary transfer roller 89. At this position, the secondary transfer backup roller 82 sandwiches the intermediate transfer belt 78 between the secondary transfer roller 89 and forms a secondary transfer nip. The four color toner images formed on the intermediate transfer belt 78 are transferred onto the recording medium P conveyed to the position of the secondary transfer nip. At this time, untransferred toner that has not been transferred to the recording medium P remains on the intermediate transfer belt 78.
Thereafter, the intermediate transfer belt 78 reaches the position of the intermediate transfer cleaning unit 80. At this position, the untransferred toner on the intermediate transfer belt 78 is collected.
Thus, a series of transfer processes performed on the intermediate transfer belt 78 is completed.

Here, the recording medium P transported to the position of the secondary transfer nip is transported from the paper feeding unit 12 disposed below the apparatus main body 1 via the paper feeding roller 97 and the registration roller pair 98. It is a thing.
Specifically, a plurality of recording media P such as transfer paper are stored in the paper supply unit 12 in an overlapping manner. When the paper feed roller 97 is rotationally driven in the counterclockwise direction in FIG. 1, the uppermost recording medium P is fed between the rollers of the registration roller pair 98.

  The recording medium P conveyed to the registration roller pair 98 is temporarily stopped at the position of the roller nip of the registration roller pair 98 that has stopped rotating. Then, the registration roller pair 98 is rotationally driven in synchronization with the color image on the intermediate transfer belt 78, and the recording medium P is conveyed toward the secondary transfer nip. In this way, a desired color image is transferred onto the recording medium P.

Thereafter, the recording medium P on which the color image has been transferred at the position of the secondary transfer nip is conveyed to the nip portion of the fixing portion 20 (where the fixing roller 21 and the pressure roller 31 are in pressure contact). The color image transferred onto the surface is fixed on the recording medium P by the heat and pressure generated by the fixing roller 21 and the pressure roller 31 at the nip portion (fixing nip portion).
Thereafter, the recording medium P is discharged out of the apparatus through a pair of paper discharge rollers 99. The transferred P discharged from the apparatus by the discharge roller pair 99 is sequentially stacked on the stack unit 100 as an output image.
Thus, a series of image forming processes in the image forming apparatus is completed.

Next, the configuration and operation of the fixing device 20 installed in the image forming apparatus main body 1 will be described in detail with reference to FIGS.
2 and 3, the fixing device 20 includes a fixing roller 21 (roller member), a pressure roller 31 (roller member), frames 41 and 42, bearings 43 and 44, a spring 50, a temperature sensor 40, a guide. It consists of a plate 35, a separation plate 38 and the like.

  Here, the fixing roller 21 as a roller member is a thin cylindrical body that rotates in the direction of the arrow in FIG. 2, and a heater 25 (heat source) as a heating means is fixed inside the cylindrical body. Yes. The fixing roller 21 is a multi-layered structure in which an elastic layer 23 and a release layer 24 are sequentially laminated on a cored bar 22, and a nip portion is formed by pressure contact with a pressure roller 31 as another roller member. To do.

The cored bar 22 of the fixing roller 21 is formed of an iron-based material such as SUS304.
The elastic layer 23 of the fixing roller 21 is made of an elastic material such as fluorine rubber, silicone rubber, or foamable silicone rubber.
Further, as the release layer 24 of the fixing roller 21, PFA (tetrafluoroethylene bar fluoroalkyl vinyl ether copolymer resin), polyimide, polyetherimide, PES (polyether sulfide), or the like can be used. By providing the release layer 24 on the surface layer of the fixing roller 21, the releasability (peelability) for the toner T (toner image) is secured.

  The heater 25 (heating means) of the fixing roller 21 is a halogen heater, and both ends thereof are fixed to the frame of the fixing device 20. Then, the fixing roller 21 is heated by the heater 25 whose output is controlled by the power supply unit (AC power supply) of the apparatus main body 1, and heat is applied to the toner image T on the recording medium P from the surface thereof. The output control of the heater 25 is performed based on the detection result of the roller surface temperature by the temperature sensor 40 (thermistor) that contacts the surface of the fixing roller 21. Specifically, the AC voltage is applied to the heater 25 for the energization time determined based on the detection result of the temperature sensor 40. By such output control of the heater 25, the temperature (fixing temperature) of the fixing roller 21 can be adjusted and controlled to a desired temperature (target control temperature). The temperature sensor 40 may be a non-contact type thermopile other than a contact type thermistor.

The pressure roller 31 as a roller member mainly includes a cored bar 32 and an elastic layer 33 formed on the outer peripheral surface of the cored bar 32 via an adhesive layer. The elastic layer 33 of the pressure roller 31 is formed of a material such as fluorine rubber, silicone rubber, or foamable silicone rubber. A thin release layer made of PFA or the like can be provided on the surface layer of the elastic layer 33.
The pressure roller 31 is in pressure contact with the fixing roller 21 by the urging force of a spring 50 as a pressure unit. In this way, a desired nip portion is formed between the two roller members (the pressure roller 31 and the fixing roller 21).

Guide plates 35 for guiding the conveyance of the recording medium P are disposed on the entrance side and the exit side of the contact portion (a nip portion) between the fixing roller 21 and the pressure roller 31, respectively. The guide plate 35 is fixed to the housing of the fixing device 20.
A separation plate 38 is disposed at a position facing the outer peripheral surface of the fixing roller 21 and in the vicinity of the exit side of the nip portion. The separation plate 38 prevents a problem that the recording medium P after the fixing process is wound around the fixing roller 21 along with the rotation of the fixing roller 21.

The fixing device 20 configured as described above operates as follows.
When the power switch of the apparatus main body 1 is turned on, AC voltage is applied (powered) from the AC power source to the heater 25, and rotation driving of the fixing roller 21 and the pressure roller 31 in the direction of the arrow in FIG. The
Thereafter, the recording medium P is fed from the paper feeding unit 12 and an unfixed image is carried on the recording medium P at the position of the secondary transfer nip. The recording medium P carrying the unfixed image T (toner image) is conveyed in the direction of the arrow Y10 in FIG. 2 and sent to the nip portion (fixing nip portion) of the fixing roller 21 and the pressure roller 31 in the pressure contact state. Entered. Then, the toner image T is fixed on the surface of the recording medium P by the heating by the fixing roller 21 and the pressing force of the fixing roller 21 and the pressure roller 31. Thereafter, the recording medium P sent out from the nip portion by the rotating fixing roller 21 and the pressure roller 31 is conveyed in the direction of the arrow Y11.

Hereinafter, the configuration and operation of the fixing device 20 that are characteristic of the first embodiment will be described with reference to FIGS.
With reference to FIGS. 3 and 4, the frames 41 and 42 of the fixing device 10 are divided into two roller members 21 and 31. The frames 41 and 42 are provided with holes 41a and 42a (through holes) for holding the bearings 43 and 44, respectively. On the other hand, bearings 43 and 44 such as ball bearings are installed on both end shaft portions 21a and 31a of the two roller members 21 and 31, respectively. The two roller members 21 and 31 are rotatably supported by the frames 41 and 42 via bearings 43 and 44, respectively.

  Specifically, the frame 41 (first frame) for the fixing roller 21 is installed independently at both ends of the fixing roller 21, and the fixing roller 21 is held in the bearing 43 (held in the hole 41a). It is supported so that it can rotate freely. Similarly, the frame 42 (second frame) for the pressure roller 31 is installed independently at both ends of the pressure roller 31, and the pressure roller 31 is held in the bearing 44 (hole 42a). .) Is supported rotatably. Note that the first frames 41 installed independently at both ends are respectively fastened to the stays (not shown) of the fixing device 20 with screws.

Then, referring to FIG. 4, both the frames 41 and 42 on which the roller members 21 and 31 are installed engage the pin A fixed to the second frame 42 with the notch portion of the first frame 41. The screw rod (spring 50 is wound around) installed on the second frame 42 is screwed into the female screw portion formed on the first frame 41 for assembly. In the fixing device 20 assembled in this way, the two roller members 21 and 31 are brought into pressure contact with each other by the urging force of the spring 50 (pressure means) with the position of the pin A as a center to form a nip portion. .
As described above, the frames 41 and 42 of the fixing device 10 are divided into two roller members 21 and 31, so that an independent unit for each of the two roller members 21 and 31 (fixing roller unit and pressure roller unit). Therefore, the workability of independent maintenance of the fixing roller 21 and the pressure roller 31 is facilitated.

  Here, referring to FIG. 4, the two roller members 21, 31 are opposed to the holes 41 a, 42 a (for holding the bearings 43, 44) of the frames 41, 42. Non-contact portions 41a2 and 42a2 (in the range of the two-dot chain line S2) formed so that the bearings 43 and 44 do not contact the hole portions 41a and 42a, and two rollers. Abutting portions 41a1 and 42a1 (in the range of the alternate long and short dash line S1) formed so that the bearings 43 and 44 abut on the holes 41a and 42a on the side opposite to the side where the members 21 and 31 face each other are formed. Has been. Specifically, the non-contact portions 41a2 and 42a2 of the holes 41a and 42a are formed over a range of ± 90 degrees or more with respect to an imaginary line segment L1 connecting the rotation centers of the two roller members 21 and 31. That is, the non-contact portions 41a2 and 42a2 are formed so as to exceed the line segments L2 and L3 (range of ± 90 degrees) orthogonal to the virtual line segment L1 described above at the position of the rotation center. More specifically, the non-contact portions 41 a 2 and 42 a 2 are formed so that the inner diameter thereof is larger than the outer diameter of the bearings 43 and 44. The contact portions 41a1 and 42a1 are formed so that the inner diameters thereof are substantially the same as the outer diameters of the bearings 43 and 44.

Such a configuration reduces the contact area between the frames 41 and 42 (holes 41a and 42a) and the bearings 43 and 44 (because they abut only within the range of the one-dot chain line S1). The contact resistance is reduced, and the bearings 43 and 44 (roller members 21 and 31) are easily moved in the thrust direction (rotational axis direction). Therefore, when the movement of the bearings 43 and 44 in the thrust direction is restricted, abnormal noise generated between the frames 41 and 42 and the bearings 43 and 44 can be suppressed.
Further, since the contact area between the frames 41 and 42 (holes 41a and 42a) and the bearings 43 and 44 is reduced (because of contact only within the range of the one-dot chain line S1), the bearings 43 are bent by the roller members 21 and 31 or the like. , 44 are less likely to interfere with the frames 41, 42 even if they vibrate in the eccentric direction (axial deviation direction), and abnormal noise due to contact between the frames 41, 42 and the bearings 43, 44 can be reduced.
Furthermore, in the first embodiment, the holes 41a and 42a are not notched, and even if the non-contact portions 41a2 and 42a2 are provided in the holes 41a and 42a, the holes 41a and 42a have a total area of the frames 41 and 42. Since the area ratio is relatively small, the strength of the frames 41 and 42 can be sufficiently secured.

  In order to further enhance the effect of suppressing the abnormal sound described above, it is preferable to apply grease to the contact portions 41a1 and 42a1. That is, by applying grease to the contact portions 41a1 and 42a1, the contact resistance between the contact portions 41a1 and 42a1 and the bearings 43 and 44 is further reduced, and the occurrence of abnormal noise is further reduced. In particular, when fluorine grease is used as the grease to be applied to the contact portions 41a1 and 42a1, the viscosity can be maintained for a long time even in the fixing device 20 in a high temperature environment. The occurrence of abnormal noise can be reduced.

Here, in the first embodiment, referring to FIG. 5, a flange portion 43 a is provided on the bearing 43 (ball bearing) of the fixing roller 21. Although illustration is omitted, a predetermined clearance is provided between the flange portion 43 a and the frame 41 in a state of being installed on the frame 41. Then, the flange 43a of the bearing 43 interferes with the frame 41, so that the movement of the bearing 43 in the rotation axis direction (the left-right direction in FIG. 5) is restricted, and the bearing 43 (fixing roller 21) from the frame 41 is regulated. The problem of falling off is suppressed. Although not shown, the pressure roller 31 side is configured similarly to the fixing roller 21 side.
In the first embodiment, the flanges that interfere with the frames 41 and 42 are provided on the bearings 43 and 44 side. However, the projections that interfere with the bearings 43 and 44 may be provided on the frame 41 and 42 side. .

In the first embodiment, referring to FIG. 5, the movement of the bearing 43 in the rotation axis direction (the left-right direction in FIG. 5) is restricted to the shaft portion 21 a (core shaft) of the fixing roller 21. A retaining ring 51 is installed so as to sandwich the bearing 43. Although not shown, the pressure roller 31 side is configured similarly to the fixing roller 21 side.
With such a configuration, the position of the bearing 43 on the shaft portion 21a of the fixing roller 21 is fixed to prevent the shaft portion 21a from being worn, and abnormalities due to stick-slip generated between the shaft portion 21a and the bearing 43 are prevented. Sound can be suppressed.

  As described above, in the first embodiment, the bearings 43 and 44 contact the holes 41a and 42a on the side where the two roller members 21 and 31 are opposed to the holes 41a and 42a of the frames 41 and 42, respectively. Since the non-contact portions 41a2 and 42a2 are provided so as not to come into contact with each other, the contact area between the frames 41 and 42 and the bearings 43 and 44 is reduced, and the bearings 43 and 44 are easily moved in the thrust direction. Even if 43 and 44 vibrate in the eccentric direction, they do not easily interfere with the frames 41 and 42. Thereby, it is possible to reduce occurrence of abnormal noise due to contact between the frames 41 and 42 and the bearings 43 and 44.

  In the first embodiment, the present invention is applied to a fixing device using the fixing roller 21 as the fixing member and the pressure roller 31 as the pressure member. However, the fixing using a fixing belt as the fixing member is used. The present invention can also be applied to an apparatus and a fixing device using a pressure belt as a pressure member. That is, even in a fixing device in which the two roller members are configured to be in pressure contact with each other via an endless belt member (a fixing belt or a pressure belt) to form a fixing nip portion. Similar to the first embodiment, by providing a non-contact portion in the hole portion of the frame that supports the two roller members, the same effect as in the first embodiment can be obtained.

Embodiment 2. FIG.
A second embodiment of the present invention will be described in detail with reference to FIG.
FIG. 6 is a side view showing the fixing device according to the second embodiment, and corresponds to FIG. 4 in the first embodiment. In the fixing device according to the second embodiment, the range of the contact portions 41a1 and 42a1 and the non-contact portions 41a2 and 42a2 formed in the holes 41a and 42a of the frames 41 and 42 is the same as that of the first embodiment. Is different.

  Similarly to the first embodiment, the fixing device 20 according to the second embodiment also has a fixing roller 21 (roller member), a pressure roller 31 (roller member), frames 41 and 42, bearings 43 and 44, springs. 50, etc. Also in the second embodiment, the contact portions 41a1 and 42a1 and the non-contact portions 41a2 and 42a2 are formed in the holes 41a and 42a of the frames 41 and 42, respectively.

Here, in the second embodiment, as shown in FIG. 6, the non-contact portions 41 a 2 and 42 a 2 formed in the holes 41 a and 42 a of the frames 41 and 42 are the rotation centers of the two roller members 21 and 31. Is formed over a range of ± 90 degrees or more and ± 140 degrees or less with respect to a virtual line segment L1 connecting the two. That is, the contact portions 41a1 and 42a1 are formed such that the angle θ (range) is 80 degrees or more.
With such a configuration, the contact between the holes 41a and 42a and the bearings 43 and 44 is maintained while maintaining the retaining ability of the bearings 43 and 44 (the contact area with the contact parts 41a and 42a) by the holes 41a and 42a. The inventor of the present application has confirmed through experiments and the like that the generation of abnormal sounds due to the above can be suppressed.

  As described above, in the second embodiment as well, in the same manner as in the first embodiment, the bearings 43, 42, 42a on the side where the two roller members 21, 31 are opposed to the holes 41a, 42a of the frames 41, 42, Since the non-contact portions 41a2 and 42a2 are provided so that 44 does not contact the holes 41a and 42a, the contact area between the frames 41 and 42 and the bearings 43 and 44 is reduced, and the bearings 43 and 44 are thrust. It becomes easy to move in the direction, and even if the bearings 43 and 44 vibrate in the eccentric direction, they do not easily interfere with the frames 41 and 42. Thereby, it is possible to reduce occurrence of abnormal noise due to contact between the frames 41 and 42 and the bearings 43 and 44.

Embodiment 3 FIG.
A third embodiment of the present invention will be described in detail with reference to FIG.
FIG. 7 is a side view illustrating the fixing device according to the third embodiment, and corresponds to FIG. 4 according to the first embodiment. The fixing device according to the third embodiment is different from that according to the first embodiment in that the contact portions 41a1 and 42a1 formed in the holes 41a and 42a of the frames 41 and 42 are divided into a plurality of portions in the circumferential direction. Is different.

  As in the first embodiment, the fixing device 20 according to the third embodiment also has a fixing roller 21 (roller member), a pressure roller 31 (roller member), frames 41 and 42, bearings 43 and 44, springs. 50, etc. Also in the third embodiment, the contact portions 41a1 and 42a1 and the non-contact portions 41a2 and 42a2 are formed in the holes 41a and 42a of the frames 41 and 42, respectively.

Here, in the third embodiment, as shown in FIG. 7, the contact portions 41a1 and 42a1 are divided into three in the circumferential direction with a gap. And between the adjacent contact parts 41a1 and 42a1, the internal diameter is formed larger than the outer diameter of the bearings 43 and 44, and it functions similarly to the non-contact part.
With such a configuration, the contact area between the frames 41 and 42 (holes 41a and 42a) and the bearings 43 and 44 is further reduced, so that abnormal noise is generated due to the contact between the frames 41 and 42 and the bearings 43 and 44. Can be further reduced.

  As described above, also in the third embodiment, the bearing 43, the two roller members 21 and 31 are opposed to the holes 41a and 42a of the frames 41 and 42 in the same manner as the above embodiments. Since the non-contact portions 41a2 and 42a2 are provided so that 44 does not contact the holes 41a and 42a, the contact area between the frames 41 and 42 and the bearings 43 and 44 is reduced, and the bearings 43 and 44 are thrust. It becomes easy to move in the direction, and even if the bearings 43 and 44 vibrate in the eccentric direction, they do not easily interfere with the frames 41 and 42. Thereby, it is possible to reduce occurrence of abnormal noise due to contact between the frames 41 and 42 and the bearings 43 and 44.

Embodiment 4 FIG.
A fourth embodiment of the present invention will be described in detail with reference to FIG.
FIG. 8 is a side view showing the fixing device in the fourth embodiment, and corresponds to FIG. 5 in the first embodiment. The fixing device according to the fourth embodiment is different from that according to the first embodiment in that a step portion is provided in the shaft portion of the roller member.

  Similarly to the first embodiment, the fixing device 20 according to the fourth embodiment also has a fixing roller 21 (roller member), a pressure roller 31 (roller member), frames 41 and 42, bearings 43 and 44, springs. 50, etc. Also in the fourth embodiment, the contact portions 41a1 and 42a1 and the non-contact portions 41a2 and 42a2 are formed in the holes 41a and 42a of the frames 41 and 42, respectively.

Here, in the fourth embodiment, as shown in FIG. 8, the movement of the bearing 43 in the rotation axis direction (the left-right direction in FIG. 8) is restricted to the shaft portion 21 a (core shaft) of the fixing roller 21. A stepped portion 21a1 is formed. Specifically, the shaft portion 21a is formed such that the outer diameter on the right side is larger than the outer diameter on the left side (a region where the bearing 43 is inserted) with the stepped portion 21a1 as a boundary. A retaining ring 51 is provided on the shaft portion 21a (core shaft) of the fixing roller 21 so as to sandwich the bearing 43 with the step portion 21a1.
With such a configuration, the position of the bearing 43 on the shaft portion 21a of the fixing roller 21 is fixed to prevent the shaft portion 21a from being worn, and abnormalities due to stick-slip generated between the shaft portion 21a and the bearing 43 are prevented. Sound can be suppressed. In particular, by providing the step portion 21a1 on the shaft portion 21a, the number of retaining rings 51 installed on the shaft portion 21a can be reduced. Although not shown, the pressure roller 31 side is configured similarly to the fixing roller 21 side.

  In the fourth embodiment, the bearing 43 is fixed on the shaft portion 21a using the step portion 21a1 and the retaining ring 51. However, the bearing 43 is pressed onto the shaft portion 21a by press-fitting the bearing 43 into the shaft portion 21a. Can also be fixed. In that case, the deformation of the shaft portion 21a due to the press-fitting of the bearing 43 can be prevented by setting the hardness of the shaft portion 21a to 70 HV or higher.

  As described above, also in the fourth embodiment, as in each of the above-described embodiments, the bearings 43, 42, 42a on the side where the two roller members 21, 31 are opposed to the holes 41a, 42a of the frames 41, 42, Since the non-contact portions 41a2 and 42a2 are provided so that 44 does not contact the holes 41a and 42a, the contact area between the frames 41 and 42 and the bearings 43 and 44 is reduced, and the bearings 43 and 44 are thrust. It becomes easy to move in the direction, and even if the bearings 43 and 44 vibrate in the eccentric direction, they do not easily interfere with the frames 41 and 42. Thereby, it is possible to reduce occurrence of abnormal noise due to contact between the frames 41 and 42 and the bearings 43 and 44.

  In each of the above embodiments, the present invention is applied to the fixing device 20 using the heater 25 as a heating unit. However, the electromagnetic induction heating type fixing device using an exciting coil as the heating unit is also used. Of course, the present invention can be applied.

  It should be noted that the present invention is not limited to the above-described embodiments, and within the scope of the technical idea of the present invention, the embodiments can be modified as appropriate in addition to those suggested in the embodiments. Is clear. In addition, the number, position, shape, and the like of the constituent members are not limited to the above embodiments, and can be set to a number, position, shape, and the like that are suitable for carrying out the present invention.

1 is an overall configuration diagram illustrating an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is a configuration diagram illustrating a fixing device installed in the image forming apparatus of FIG. 1. FIG. 2 is a perspective view showing a fixing device. It is a side view showing a fixing device. FIG. 3 is a cross-sectional view illustrating a fixing roller. It is a side view which shows the fixing device in Embodiment 2 of this invention. It is a side view which shows the fixing device in Embodiment 3 of this invention. It is sectional drawing which shows the fixing roller installed in the fixing device in Embodiment 4 of this invention.

Explanation of symbols

1 image forming apparatus body (apparatus body),
20 fixing device,
21 fixing roller (roller member),
21a, 31a shank,
21a1 step,
25 heater (heating means),
31 Pressure roller (roller member),
41, 42 frames,
41a, 42a hole,
41a1, 42a1 contact part, 41a2, 42a2 non-contact part,
43, 44 bearings,
43a collar part,
50 Spring (pressurizing means),
51 Retaining ring, P Recording medium.

Claims (18)

A fixing device that heats and melts a toner image and fixes the toner image on a recording medium,
Two roller members that form a nip portion to which a recording medium is conveyed by pressure contact with a pressure unit;
Bearings respectively installed on both end shaft portions of the two roller members;
A frame having a hole for holding the bearing, and rotatably supporting the two roller members via the bearing;
With
The hole of the frame is
A non-contact portion formed so that the bearing does not contact the hole on the side where the two roller members face each other;
An abutting portion formed such that the bearing abuts against the hole portion on the opposite side of the opposite side of the two roller members;
A fixing device comprising:   The fixing device according to claim 1, wherein the non-contact portion of the hole portion is formed over a range of ± 90 degrees or more with respect to an imaginary line segment connecting the rotation centers of the two roller members. .   The fixing device according to claim 2, wherein the non-contact portion of the hole portion is formed over a range of ± 140 degrees or less with respect to the virtual line segment.   The fixing device according to claim 1, wherein the contact portion of the hole portion is divided into a plurality of portions in a circumferential direction.   The fixing device according to claim 1, wherein grease is applied to the contact portion of the hole portion.   The fixing device according to claim 5, wherein the grease is fluorine grease.   The fixing device according to claim 1, wherein the bearing includes a flange that interferes with the frame and restricts movement of the roller member in a rotation axis direction.   8. The fixing device according to claim 1, wherein the shaft portion of the roller member is provided with a retaining ring that restricts movement of the bearing in the rotation axis direction with respect to the roller member. .   9. The fixing device according to claim 1, wherein the shaft portion of the roller member is formed with a step portion that restricts movement of the bearing in the rotation axis direction with respect to the roller member. .   The fixing device according to claim 1, wherein the bearing is press-fitted into the shaft portion of the roller member.   The fixing device according to claim 10, wherein the shaft portion of the roller member is formed to have a hardness of 70 HV or more. The non-contact portion of the hole is formed such that an inner diameter thereof is larger than an outer diameter of the bearing,
The fixing device according to claim 1, wherein the contact portion of the hole portion is formed so that an inner diameter thereof is the same as an outer diameter of the bearing.   The fixing device according to claim 1, wherein the frame is divided for each of the two roller members.   The fixing device according to claim 1, wherein the frame is installed independently at both ends of the two roller members.   The fixing device according to claim 1, wherein the two roller members are a fixing roller and a pressure roller.   The fixing device according to claim 1, wherein the two roller members are pressed against each other via an endless belt member to form the nip portion.   An image forming apparatus comprising the fixing device according to claim 1. A frame installed in a fixing device for fixing a toner image on a recording medium by heating and melting;
Comprising holes for holding bearings respectively installed on both end shaft portions of two roller members forming a nip portion to which a recording medium is conveyed by being pressed by a pressing means;
The two roller members are rotatably supported via the bearings,
The hole is
A non-contact portion formed so that the bearing does not contact the hole on the side where the two roller members face each other;
An abutting portion formed such that the bearing abuts against the hole portion on the opposite side of the opposite side of the two roller members;
A frame characterized by comprising:

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